ES2626799T3 - Lightweight construction of a diesel piston - Google Patents

Abstract

Piston (10) for a combustion engine with a plunger bottom (22), a cylindrical plunger head (11), which is connected to the plunger bottom (22), and a piston body (40) at least partially hollow, which is formed in the piston head (11) on the side facing away from the piston bottom (22) and which has two opposite body wall sections (50) as well as two opposite connecting walls (60) , which connect the body wall sections (50), the connecting walls (60) presenting in each case a bolt hole (61), the piston head (11) presenting a cooling channel (18) in the form of ring with at least one intake opening (28) and at least one discharge opening (30), the two body wall sections (50) widening in each case towards the plunger head (11), so that the length sector (L1) of the side formed on the plunger head (11) of the body wall section (50) is greater than the length sector tud (L2) on the side facing away from the piston head (11) of the body wall section (50), two reinforcing ribs (45) being formed, which run mostly parallel to the axis of bolt or arc-shaped and extend essentially from a bolt hole (61a) to another bolt hole (61a), in the piston head (11) and extend in the hollow space of the piston body (40 ), and the intake opening (28) and the discharge opening (30) being provided in each case between a reinforcing rib (45) and the nearest body wall section (50).

Description

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DESCRIPTION

Light construction of a diesel piston Technical field

The invention relates to a plunger for a combustion engine, in particular for a diesel engine. The plunger is designed in particular as a cast iron plunger, for example aluminum or an aluminum alloy.

State of the art

With the increasing performance optimization and / or optimization of combustion engine consumption, the thermal and mechanical loads on the emboli increase. Precisely with respect to the optimization of consumption it is desirable to maintain or even improve the load capacity and durability of the plunger itself even in the case of a reduction in the weight of the plunger. To this end, different approaches are followed that are within an optimization of the embolus material, for example aluminum alloy, an improvement of the cooling architecture and other measures.

For example, document DE 10 2009 027 148 A1 describes an improvement in the cooling architecture. Another approach with respect to weight / performance optimization is described in DE 10 2007 058 789 A1, in which the particular design of reinforcing ribs leads to a reduction in the weight of the embolus, without affecting in this respect the resistance of the plunger.

With regard to an optimization of combustion engine consumption, other measures for reducing the weight of the plunger are desirable while maintaining or even improving the mechanical and thermal resistance.

Exhibition of the invention

An object of the invention is to provide a plunger, in particular an aluminum cast iron or an aluminum alloy, which is optimized with respect to thermal / mechanical resistance as well as weight.

The objective is achieved with a stroke with the features of claim 1.

The embolus according to the invention has a plunger bottom, a cylindrical plunger head, which is connected at the plunger bottom, and an at least partially hollow plunger body, which is formed in the plunger head on the direction-oriented side opposite the plunger bottom and having two opposite body wall sections as well as two opposite connection walls, which connect the body wall sections, the connection walls in each case having a bolt hole. A ring-shaped cooling channel with at least one intake opening and at least one discharge opening is provided on the plunger head. In addition, the body wall sections are widened in each case towards the plunger head, so that the sector length of the width formed in the plunger head of the body wall section is greater than the sector length of the side oriented opposite to the plunger head of the body wall section.

With "sector length" in this case refers to the length, with which the corresponding body wall section extends along the cylindrical penimeter of the embolus. The designations "intake opening" and "discharge opening" can still be understood as synonymous, since the inlet and outlet in the cooling channel can be exchanged or both openings can simultaneously serve as inputs and outputs.

The invention aims to achieve the objective through a synergistic interaction of several measures, that is to say from a broader vision in comparison with the state of the art. This is achieved because a refrigeration architecture is combined, by which temperatures can be effectively reduced and thus the thermal and mechanical loads in the area of the embolus bottom, with a design of the embolus body optimized for the refrigeration architecture. The widening of the body wall sections towards the plunger head produces a stabilization in the high load areas, while at the same time allowing a return movement of the connecting walls inwards, thereby saving weight, due to at the reduced distance thereby between the two bolt holes. The weight saving is based on the one hand that, by shifting the connecting walls inwards, the perimeter length or sleeve surface of the plunger body is reduced. On the other hand, the wall thicknesses of the plunger body can be reduced, since the distribution of forces due to the reduced distance between the two bolt holes is more favorable. In this sense, it is important that the design of the embolus body described above develops the effects described and can be implemented with considerable weight savings only when cooling of the embolus head takes place.

Preferably, the intake opening and / or the discharge opening of the ring-shaped cooling channel

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It is located in the area of a body wall section and / or in the area of a connecting wall. With this, the cooling oil jet can be guided on the inner side of the corresponding body wall section and / or on the inner side of the corresponding connection wall, whereby the oil jet can be injected with low loss in the cooling channel With this, an extremely effective cooling takes place, which in turn allows an optimization of the design of the embolus body.

Preferably, the shortest sector length of at least one of the body wall sections is between the side formed on the plunger head and the side facing away from the plunger head. In other words, the edge of the corresponding body wall section, which is oriented in the opposite direction to the plunger head, does not have the shortest sector length. Rather, a narrowing of the body wall section (starting from the embolus bottom) takes place at a minimum sector length and then another widening, whereby an optimization of the fastening of the corresponding body wall section takes place to the connection walls.

Preferably, the sector length described above is closer to the side of the plunger head than to the side facing away from the plunger head. In other words, starting from the plunger head, a rapid narrowing of the corresponding body wall section takes place first, then a slow broadening. With this body wall geometry an additional optimization takes place with respect to the relationship between the weight and the stability of the plunger.

Preferably, the body wall sections each have two edges that connect the side formed in the plunger head of the body wall section with the side facing away from the plunger head of the same wall section of body, presenting the edges, starting from the bottom of the plunger, a curved section convexly. The convex curvature establishes the fastening of the body wall section in the area of the plunger head to the corresponding connection walls, whereby the strength and durability of the plunger with an unmodified or hardly modified weight are improved.

Preferably, the convexly curved sections of the edges in each case become a concave curvature and then extend essentially in straight line. In this case, a curvature in the non-adjacent environment of the plunger head is not unconditionally necessary for attachment to the connection walls.

Preferably, the straight sections do not run in parallel, rather the distance increases from the minimum sector length to the side of the body section, which is oriented in the opposite direction to the plunger head. The spacing preferably takes place with a smaller or even clearly smaller inclination compared to the convex section. The spacing described in this case represents a good compromise of embolus body stability and weight savings.

Preferably, the connecting walls have in each case a bolt bushing, in which the bolt hole in question is found, the bolt bushes having an increased wall thickness compared to other sections of the connecting walls. The bolt drilling zones are high mechanical and thermal load zones. Therefore, it is important with respect to the stability of the bolt that the bolt bushings have a large wall thickness. Other sections, also such sections that represent a connection with the body wall sections or a conversion in the body wall sections, may in comparison with these have a smaller wall thickness, without appreciably damaging the stability of the plunger. The particular concentration of the material of the plunger body in the bolt perforations is favored because the body wall sections according to the invention allow a return movement of the connection walls in the direction of the internal part of the body. For additional reinforcement of the bolt bushings, they can be equipped in each case with a brass bushing.

Preferably, the bolt bushings extend from the thinner wall thickness sections of the connection walls in question essentially outward. By means of the design of the plunger body described above, the connection walls can be moved very broadly to the inner part, which is advantageous with respect to a weight saving as set forth above. In this way, the bolt bushings protrude outwards in comparison with the thinner sections in this respect of the connection walls.

Preferably, the plunger is made of aluminum or an aluminum alloy. Forged emboli have a more compact metal structure in comparison with foundry emboli in general, thus being, in the case of comparable strength, lighter than cast iron emboli. Consequently, measures for weight reduction play a very important role precisely in the case of cast iron embos, for example of an aluminum alloy. Therefore, the expert does not generally consider structural characteristics of one-to-one transmission of a plunger forged to a cast plunger.

Preferably, two reinforcing ribs are provided, which run mostly parallel to the bolt axis, are formed in the plunger head and extend into the hollow space of the plunger body. The nerves of

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reinforcement stabilize on the one hand the body of plunger in areas of high load. On the other hand, they allow a reduction in the wall thickness of the embolus body and with it, despite the additional material for the reinforcement ribs, a reduction in the total weight. The reinforcing ribs can be configured quite small, so that they extend, according to a preferred embodiment, only approximately at most up to the lower vertex (i.e. the vertex that is closest to the plunger head) of Bolt holes in the plunger body. The reinforcing ribs are preferably formed in the bolt bushings and connect these continuously. In the areas of the support, the reinforcement ribs may have an increased wall thickness.

Preferably, the reinforcing ribs are shaped in an arc, extend essentially from a bolt hole to another bolt hole, are formed in the plunger head and extend into the hollow space of the plunger body. Additionally or alternatively to the features discussed above, which refer to the reinforcing ribs, these are preferably curved along their extension direction parallel to the embolus bottom, whereby an improvement of the mechanical strength is obtained. and the durability of the embolus.

The intake opening and the discharge opening are between a reinforcement rib and the nearest body section. In this way, another better guidance of the injection oil jet is possible, which leads to an improved cooling effect and thereby an improvement in the thermal and mechanical resistance of the plunger.

The invention was described by a lightweight construction plunger. From the following description of preferred embodiments, advantages and additional features of the invention become apparent. The features described theref and above can be implemented individually or in combination, provided that the features are not contradicted. In this regard, the following description of the preferred embodiments takes place with reference to the accompanying drawings.

Brief description of the figures

Figure 1 is a three-dimensional representation of a bolo embolus from above;

Figure 2 shows the plunger of Figure 1 in a partially transparent form of representation;

Figure 3 shows the plunger of Figure 1 bias from below;

Figure 4 is a side view of the plunger of Figure 1;

Figure 5 is another side view of the plunger of Figure 1;

Figure 6 shows the plunger of Figure 1 from below;

Figure 7 is a sectional view of the plunger of Figure 1;

Figure 8 is a three-dimensional view of the plunger cut out of Figure 1;

Figure 9 is a side view of a plunger according to a second embodiment;

Figure 10 shows the plunger of Figure 9 from below;

Figure 11 is an additional side view of the plunger of Figure 9;

Figure 12 shows a plunger not according to the invention from below;

Figure 13 shows the plunger of Figure 12 from the side;

Figure 14 is an additional side view of the plunger of Figure 12;

Figure 15 shows the plunger of Figure 12 bias from below.

Modes for carrying out the invention

Figures 1 to 8 show a plunger 10 according to a first embodiment in different views and perspectives. Reference numbers are used homogeneously and are not described again for each figure. In addition, some reference numbers have been deleted in one view or another, if necessary for reasons of clarity.

Figure 1 shows the plunger 10 in a three-dimensional view on the bias from above. The plunger 10, which is preferably made of cast aluminum or an aluminum alloy, has a chamber cavity of

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combustion 12, which in the present example is in the form of a ro, as can be seen in a particularly clear way from Figure 7. There is shown the plunger 10 in a sectional view. Starting from the bottom of plunger 22, the combustion chamber cavity 12 extends into the plunger head 11. The curvature of the wall that configures the combustion chamber cavity 12 is first convex, then it becomes a curvature concave, which strikes not only the depth but also the width of the plunger head 11, then presents an approximately straight section, which becomes a projection that is in the center (of the middle projection of the O"). This curved development is symmetrical in terms of rotation, that is, in the section of Figure 7, symmetrically specular in relation to the middle axis of the plunger 10.

Several annular grooves 14 are provided for plunger rings not shown. Perforations, blind holes, through openings or other openings 15 may be incorporated in one or more of the annular grooves 14, to improve the supply of oil in the plunger and the internal part of the body. Oil can be transported through the openings 15, which is released from the plunger rings not shown, for example to the inner part of the plunger.

In the plunger head 11 there is a ring-shaped cooling channel 18, which is shown in Figure 2 and is also deduced from Figures 7 and 8. The cooling channel 18 runs approximately circularly and concentrically with respect to to the cylindrical penimeter of the plunger 10. The diameter of the cooling channel ring is adapted so that it is provided near the greatest depths of the combustion chamber cavity 12 and at the same time has a sufficient distance so as not to damage the mechanical resistance of the plunger head 11 due to a possible thin wall thickness between the combustion chamber cavity 12 and the cooling channel 18. From Figure 2, it is evident that the cooling channel 18 does not have to run in a mandatory manner exactly in a plane that is present parallel to the bottom of plunger 22. Rather, the cooling channel 18 in the present example has an arcuate shape, in which the z High waves and deep areas (in the direction of the plunger axis) are connected to each other in a gently curved manner.

The cooling channel 18 has a cooling medium intake opening 28 and a cooling medium discharge opening 30. The cooling medium intake opening 28 and the cooling medium discharge opening 30 extend into the space hole of the plunger 10, which is defined by the plunger body 40 and is further described in more detail below. Preferably, the cooling medium intake opening 28 and the cooling medium discharge opening 30 are provided in the deep areas of the cooling channel 18, as shown in Figure 2. In the intake opening of the cooling medium refrigeration 28 or the discharge opening of cooling medium 30 can be injected cooling medium actively through an injector not shown. Additionally or alternatively, the supply may take place through an injection oil. In addition, the cooling medium comes out of the intake opening of cooling medium 28 and / or the discharge opening of cooling medium 30 and reaches, due to the favorable position of the openings, areas to be cooled and going to lubricate the plunger bolt, the bolt support in the bolt holes and the connection between the plunger bolt and the connecting rod eye. For reasons of clarity, a representation of the plunger bolt and connecting rod has been omitted.

The plunger body 40 has two opposite body wall sections 50 and two opposite connection walls 60, which connect the body wall sections 50. The connection walls 60 are offset with respect to the cylindrical plunger body 11 inwardly, so that the entire contour in the section of figure 6 of the plunger body 40 does not adopt any circular cylinder shape, but rather a rectangular shape. In this sense, the body wall sections 50, however, have a circular cylindrical arc according to the circular cylindrical contour of the plunger head 11, which becomes essentially straight connection walls 60. In this regard, it should be noted that the connection walls 60 do not have to be exactly straight, but, as is particularly clear from Figure 6, they may be slightly curved or arched. Particularly in the connection areas with the body wall sections 50, the connection walls 60 have an outwardly directed curvature, whereby the connection areas between the body wall section 50 and the connection wall 60 can be separated for stabilization.

By moving the connection walls 60 inwards, the hollow space 41 of the plunger body 40 is comparatively narrow. In the connection walls 60, a bolt hole 61 is provided in each case, which is reinforced with bolt bushings 62. The bolt holes 61 can have one or several lateral notches (lateral incidence) 64. On the bottom side of the plunger 10, the bolt bushings 62 are flattened, as can be seen in a particularly clear manner in Fig. 6. Bolt holes 61 may be equipped with a safety ring, which is incorporated in a groove 63 configured in bolt hole 61 .

In parallel to the bolt axis, which is predetermined by the two bolt perforations 61, two reinforcement ribs 45 extend. The two reinforcement ribs 45 are provided symmetrically on both sides of the bolt not shown and connect the walls of opposite connection 60 in the area of the rear side of the bolt bushing 62. The reinforcing ribs 45 extend in the hollow space of the plunger body 40. In the present example,

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these end at the height along the axis of the plunger approximately where the apex of the bolt hole 61 is located closest to the plunger head 11. The reinforcing ribs 45 extend in the cut, shown in figure 6, approximately in straight line along the bolt axis. The upper edges of the reinforcing ribs 45, that is to say the edges, which are oriented in the opposite direction to the plunger head 11, are rounded. In addition, the reinforcement ribs 45 widen in the area of their attachment to the connection walls 60. In total, all the fasteners of the different components of the plunger body 40 are made smoothly, that is to say edges and corners are avoided. sharp, to reduce the appearance of cracks and fractures in these sensitive areas. In addition, openings 67 in the reinforcing ribs 45 or other body sections may be provided to improve the circulation of oil or the circulation of cooling medium in the plunger body 40.

The reinforcing ribs do not have to run straight along the axis of the bolt, as can be deduced from Figure 10, which together with Figures 9 and 11 represents a second embodiment. In them, the reference numbers, which correspond to the components of the first embodiment, are provided with an "a". The reinforcing ribs 45a are configured in a curved manner in the direction of the bolt axis, following the curvature of the cylindrical development of the plunger head 11, that is the reinforcing ribs 45a are seen from the axis of the plunger curved in a convex manner. With the curvature shown in Figure 10 of the reinforcing ribs 45a, the stability of the plunger 10a is further improved, without increasing the total weight.

In the embodiment, shown in Figures 9 and 10, the body wall sections 50a are also made in a bulging manner. In this sense, the internal contour of the body wall sections has an arcuate shape in the cut of Figure 10, so that a widening of the body wall sections takes place, with the greatest thickness in the middle axis of the plunger, which is perpendicular to the axis of the bolt and the axis of the plunger.

The particular shape of the body wall sections 50 is clearly deduced from Fig. 5. In the area of the fastening of the body wall section 50 at the plunger head 11, a widening 51 is provided. In other words, the Sector sector length L1 in the area of the fastener at the plunger head 11 is greater than the sector length L2 of the opposite edge 54, ie the edge of the body wall section 50, which is opposite the head of plunger 11. Starting from the clamping area in the plunger head 11, a rapid narrowing takes place first to a minimum sector length L3 through section 52. Sections 52 are convexly curved and become in the area of the minimum sector length L3 in concave curved sections. Straight sections 53 are connected thereto, which do not run parallel, but gradually diverge to the length of sector L2. In this case it is valid: L1> L2> L3

As can be deduced from Figure 5, the edge 54 can run irregularly, that is to say it can have depths, slopes, curvatures of different nature and the like. In this case, the notch 55a can be indicated by way of example in Figures 9 and 11, which guarantees the correct speech of the plunger in a cooling medium injector located in the area of the notch for injecting cooling oil into the opening of admission of cooling medium 28a.

With the design described above and represented in the figures of the body wall sections 50, a perfect fastening to the connection walls 60 takes place, whereby high stability and resistance is achieved with a simultaneous reduction of the weight of the plunger. As can be deduced from Figure 6, the cooling air intake opening 28 and the cooling medium discharge opening 30 are provided between the reinforcement ribs 45 and the nearest body wall section 50. In addition, these are in the connection zone between the body wall section 50 and the connection wall 60, that is to say in the corner between the two, whereby a perfect guidance of the admission of cooling medium to along the corresponding inner walls of the plunger body 40. Accordingly, the openings 28, 30 are offset from the middle axis of the plunger 10, which runs perpendicular to the axis of the bolt and perpendicular to the axis of the plunger. In this way, a precise injection is simplified by means of an injector not shown, so the cooling effect is improved. It may be indicated at this point that the designations "cooling media intake opening" and "cooling media discharge opening" can still be understood as synonymous, since the inlet and outlet can be exchanged or both openings can serve the Same time as inputs and outputs.

Figures 12 to 15 show different views of a plunger not according to the invention.

In them, the reference numbers, which correspond to the components of the first embodiment, are provided with a "b".

The cooling medium intake opening 28b and the cooling medium discharge opening 30b are not provided in the connection area of the body edge section 50b and the connection wall 60b nor between the plunger body 40 and the nearest reinforcement rib, but the cooling medium inlet 28b is outside the plunger body 40 in the area of the connection between the bolt bushing 62b and the connection wall 60b. In addition, the discharge opening of cooling medium 30b is approximately in the plane

The plunger parting in half, which is perpendicular to the axis of the bolt, and between the body wall section 50b, which is far from the intake opening of cooling medium 28b, and in which the rib of 45b closer reinforcement.

5 In Figure 15, the plunger is shown in bias from below. In this case, the bolt bushing 62b closest to the cooling medium intake opening 28b has a notch 29b, which facilitates the introduction of the cooling oil into the cooling media intake opening 28b. The other bolt bushing 62b has a reinforcement 63b for stabilization.

10 In addition to the position of the intake opening of the cooling medium, the discharge opening of the cooling medium and the shape and condition of the reinforcement ribs, the embodiments also differ in the shape of the sections of body wall From figure 9, which contains a side view of the second embodiment, it follows that, starting from the fastening area in the plunger head, no convex curvature of sections 52 has to be present, but these they can be curved in a concave manner, narrow rapidly and extend to the straight sections 53 following them, which do not run in parallel but gradually diverging. From figure 14 of the third embodiment, a smoothly wavy form is derived from sections 52.

To avoid redundancy, the description of the second embodiment has been made in less detail than the 20 of the first embodiment. Therefore, it should be explicitly stated that the technical characteristics and effects of the first embodiment are also valid for the second embodiment, provided that the representations of the first embodiment are not contradicted.

Claims (8)

10 fifteen twenty 25 2. 30 3. Four. 35 5. 40 6. Four. Five 7. fifty 8. 55 9. 60 10. Plunger (10) for a combustion engine with a plunger bottom (22), a cylindrical plunger head (11), which is connected at the plunger bottom (22), and a plunger body (40) at least partially hollow, which is formed in the plunger head (11) on the side facing away from the plunger bottom (22) and which has two opposite body wall sections (50) as well as two opposite connecting walls (60) , which connect the body wall sections (50), the connection walls (60) presenting in each case a bolt hole (61), the plunger head (11) having a ring-shaped cooling channel (18) with at least one intake opening (28) and at least one discharge opening (30), the two body wall sections (50) widening in each case towards the plunger head (11), so that the sector length (L1) of the side formed on the plunger head (11) of the wall section of body (50) is greater than the sector length (L2) of the side facing away from the plunger head (11) of the body wall section (50), two reinforcing ribs (45) being formed, which run mostly parallel to the bolt axis or run in an arc shape and extend essentially from a bolt hole (61a) to another bolt hole (61a), in the plunger head (11) and extend into the hollow space of the plunger body (40), and the intake opening (28) and the discharge opening (30) being provided in each case between a reinforcing rib (45) and the nearest body wall section (50). Embolus (10) according to claim 1, characterized in that the intake opening (28) and / or the discharge opening (30) is in the area of a body wall section (50) and / or in the area of a connection wall (60). Embolus (10) according to claim 1 or 2, characterized in that the shorter sector length (L3) of at least one of the body wall sections (50) is between the side formed in the plunger head (11) and the side oriented in the opposite direction to the plunger head (11). Embolus (10) according to claim 3, characterized in that the shorter sector length (L3) is closer to the side formed in the plunger head (11) than to the side oriented in the opposite direction to the plunger head (11) . Embolus (10) according to one of the preceding claims, characterized in that the body wall sections (50) have two edges connecting the side formed in the plunger head (11) of the body wall section (50) with the side oriented opposite the plunger head (11) of the same body wall section (50), the edges that start from the plunger head (11) having a convexly curved section. Embolus (10) according to claim 5, characterized in that the convexly curved sections of the edges in each case become a concave curvature and then extend essentially in straight line. Embolus (10) according to claim 6, characterized in that the straight sections of the edges do not run in parallel and / or increase their distance with respect to the side of the body wall section (50) that is oriented in the opposite direction to the head of plunger (11). Embolus (10) according to one of the preceding claims, characterized in that the connecting walls (60) each have a bolt bushing (62), in which the bolt hole (61) is in question and has a thickness of increased wall. Embolus (10) according to claim 8, characterized in that the bolt bushings (62) extend from the thinner wall thickness sections of the connection walls (60) in question essentially outward. Embolo (10) according to one of the preceding claims, characterized in that it is made of aluminum or an aluminum alloy.